I need to write recursive function to count amount of odd numbers in the sequence
Here my initial code:
program OddNumbers;
{$APPTYPE CONSOLE}
uses
SysUtils;
function GetOddNumbersAmount(const x: array of integer; count,i:integer):integer;
begin
if((x[i] <> 0) and (x[i] mod 2=0)) then
begin
count:= count + 1;
GetOddNumbersAmount:=count;
end;
i:=i+1;
GetOddNumbersAmount:=GetOddNumbersAmount(x, count, i);
end;
var X: array[1..10] of integer;
i,amount: integer;
begin
writeln('Enter your sequence:');
for i:=1 to 10 do
read(X[i]);
amount:= GetOddNumbersAmount(X, 0, 1);
writeln('Amount of odd numbers: ', amount);
readln;
readln;
end.
When i type the sequence and press "enter", program closed without any errors and i can't see the result.
Also, i think my function isn't correct.
Can someone help with that code?
UPD:
function GetOddNumbersAmount(const x: array of integer; count,i:integer):integer;
begin
if((x[i] <> 0) and (x[i] mod 2<>0)) then
count:= count + 1;
if(i = 10) then
GetOddNumbersAmount:=count
else
GetOddNumbersAmount:=GetOddNumbersAmount(x, count, i+1);
end;
You don't provide an end of recursion, i.e., you always call your function GetOddNumbersAmount again, and your program never terminates. Thus, you get an array index error (or a stack overflow) and your program crashes.
Please note, that every recursion need a case where it terminates, i.e. does not call itself. In your case, it should return if there are no elements in the array left.
In addition, you are counting the even numbers, not the odd ones.
You passed a static array to a dynamic so the index get confused:
Allocat the array with
SetLength(X,10)
allocates an array of 10 integers, indexed 0 to 9.
Dynamic arrays are always integer-indexed, always starting from 0!
SetLength(X,10)
for it:=0 to 9 do begin
X[it]:= random(100);
And second if you know the length a loop has more advantages:
function GetEvenNumbersAmount(const x: array of integer; count,i:integer):integer;
begin
for i:= 0 to length(X)-1 do
if((x[i] <> 0) and (x[i] mod 2=0)) then begin
inc(count);
//write(inttostr(X[i-1])+ ' ') :debug
end;
result:=count;
end;
Related
I am writing this code in Ada for a class where we have to teach ourselves the code. I understand heap sort, but the Ada syntax is really confusing me. I don't understand why I am getting a constraint error in this sort function.
Essentially we have to pass array "A" into this procedure, and it should organize it. I get the constraint error at siftDown(A(Start...A'Last));
Thank you in advance
Procedure sort_3(A : in out array_type) is
procedure swap(Left : in out Integer; Right : in out Integer) is
temp : Integer;
begin
temp := Left;
Left := Right;
Right := Temp;
end swap;
procedure siftDown(A : in out array_type) is
Count : Integer := 1;
root : Integer := Integer'Pos(A'First);
child : Integer := Integer'Pos(A'Last);
last : Integer := Integer'Pos(A'Last);
begin
while root * 2 + 1 <= last loop
child := root * 2 + 1;
if child + 1 <= last and then A(Integer'Val(child)) < A(Integer'Val(child + 1)) then
child := child + 1;
end if;
if A(Integer'Val(root)) < A(Integer'Val(child)) then
swap(A(Integer'Val(root)), A(Integer'Val(child)));
root := child;
else
exit;
end if;
end loop;
end siftDown;
procedure heapify(A : in out array_type) is
Count : Integer := 0;
First_Pos : Integer;
Last_Pos : Integer;
Start : Integer;
begin
First_Pos := A'First;
Last_Pos := A'Last;
Start := Integer'Val((Last_Pos - First_Pos + 1) / 2);
loop
siftDown(A(Start...A'Last));
if Start > Integer'First then
Start := Integer'Pred(Start);
else
exit;
end if;
end loop;
end heapify;
Last_Index : Integer := Integer'Last;
begin
heapify(A);
while Last_Index > Integer'First loop
swap(A(Last_Index), A(A'First));
Last_Index := Integer'Pred(Last_Index);
siftDown(A(A'First..Last_Index));
end loop;
end sort_3;
You have a syntax error in the code - an extra dot in A(Start...A'Last).
The syntax A(Start..A'Last) means a slice, part of array from Start to the last element. The Constraint_Error means that Start not in array bounds. Try to add
Ada.Text_IO.Put_Line (Start'Image);
before that line and you will see Start values and when it became out of the A'Range.
Your code has some references to Integer'First and Integer'Last, which are huge values that have nothing to do with the array A and its values. I'm pretty sure you should use A'First and A'Last instead.
Also a note on style: Using the same identifier, "A", for the parameter of the local (inner, nested) procedures as for the parameter "A" of the containing (outer) procedure, when these arrays can be different, invites confusion and errors. Better to use different identifiers.
In this code, I am asking the user to input two integers (Index, Mindex) and then I display all the integers between 1..Index and 1..Mindex. What my problem is here that I do not know how to multiply the values of Integers in Index and Integers in `Mindex and then add up the product of these two together
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Add is
Index, Mindex : Integer;
procedure calc (Item : in Integer) is
New_Value : Integer;
begin
Put ("The value of the index is now");
Put (Item);
New_Line;
New_Value := (Item - 1);
if New_Value > 0 then
calc (New_Value);
end if;
end calc;
begin
Get (Index);
Get (Mindex);
calc (Index);
New_Line;
calc (Mindex);
end Add;
A factorial keeps chaining multiplication with each decreasing value: 5! = 5 * 4 * 3 * 2 * 1 = 120. In order to do the recursion, you'll need to have two cases inside your recursive function: If your value is above 1, then multiply that value with the next smallest number. That's the recursive part where you will call Factorial(N-1) inside of Factorial(N). Otherwise just return 1 (factorial of 0 is 1 mathematically, so both 1! and 0! equal 1).
The way this works in Ada is:
function Factorial(Value : Natural) return Natural is
begin
if Value > 1 then
-- Keep chaining the multiplication with recursion
return Value * Factorial(Value - 1);
else
-- No need to chain as the result is always 1
return 1;
end if;
end Factorial;
You can then call that Factorial function on each of your numbers and add the results.
CREATE OR REPLACE FUNCTION printsum(n IN number) IS
res number:=0;
BEGIN
while(n>0)
LOOP
res:=res+n;
n:=n-1;
EXIT WHEN n=0;
END LOOP;
dbms_output.put_line(' result of sum: '||res);
END;
/
I'm trying to print sum of n numbers, but I'm getting the following error:
Warning: Function created with compilation errors.
Two things:
number strictly speaking is not necessarily integral so best to use pls_integer or at least check in the code that the passed in argument is integral
if the question is asking how to return the sum of the first n positive integers, the correct answer is to used the closed form formula: n * (n + 1)/2
Using the formula gives you a constant time answer.
function printsum(n pls_integer) return n is
begin
if(n < 0) then raise value_error; end if; -- or a more meaningful exception
return (n * (n + 1) / 2);
end;
There are few errors in your code.
1) Function must have a Return but your code had missing Return statement at beginning and at end.
2) IN parameter cannot be reassigned inside the code. So you need to copy the IN parameter to a variable to iterate.
Try this:
CREATE OR REPLACE FUNCTION printsum( n IN NUMBER)
RETURN NUMBER
IS
res NUMBER:=0;
v_num NUMBER:=n;
BEGIN
WHILE(v_num>0)
LOOP
res := res + v_num;
v_num := v_num -1;
EXIT WHEN v_num=0;
END LOOP;
dbms_output.put_line(' result of sum: '||res);
RETURN(res);
END;
/
Output:
SQL> select printsum(10) from dual;
PRINTSUM(10)
------------
55
The following code snippet is the solution:
declare
sm number;
tmp number;
n number;
i number;
function sumn(n integer)
return number
is
sm number;
begin
sm:=0;
tmp:=n;
for i in 1..tmp LOOP
sm:=sm+i;
END LOOP;
return sm;
END;
begin
n:=10;
sm:=sumn(n);
dbms_output.put_line('sum is',sm);
end;
/
I'm trying to use the concept of recursion but using for do loop. However my program cannot do it. For example if I want the output for 4! the answer should be 24 but my output is 12. Can somebody please help me?
program pastYear;
var
n,i:integer;
function calculateFactorial ( A:integer):real;
begin
if A=0 then
calculateFactorial := 1.0
else
for i:= A downto 1 do
begin
j:= A-1;
calculateFactorial:= A*j;
end;
end;
begin
writeln( ' Please enter a number ');
readln ( n);
writeln ( calculateFactorial(n):2:2);
readln;
end.
There are several problems in your code.
First of all it doesn't compile because you are accessing the undefined variable j.
Calculating the factorial using a loop is the iterative way of doing it. You are looking for the recursive way.
What is a recursion? A recursive function calls itself. So in your case calculateFactorial needs a call to itself.
How is the factorial function declared?
In words:
The factorial of n is declared as
1 when n equals 0
the factorial of n-1 multiplied with n when n is greater than 0
So you see the definition of the factorial function is already recursive since it's referring to itself when n is greater than 0.
This can be adopted to Pascal code:
function Factorial(n: integer): integer;
begin
if n = 0 then
Result := 1
else if n > 0 then
Result := Factorial(n - 1) * n;
end;
No we can do a few optimizations:
The factorial function doesn't work with negative numbers. So we change the datatype from integer (which can represent negative numbers) to longword (which can represent only positive numbers).
The largest value that a longword can store is 4294967295 which is twice as big as a longint can store.
Now as we don't need to care about negative numbers we can reduce one if statement.
The result looks like this:
function Factorial(n: longword): longword;
begin
if n = 0 then
Result := 1
else
Result := Factorial(n - 1) * n;
end;
So I have been given an assignment to read in a file put the numbers into two matrices, multiply the matrices, and finally put the output into a .txt file.
I have never used Ada before and I figured it would be a good challenge. I am stuck in trying to determine the bounds for the two separate arrays.
This is what I currently have:
currentSpread := I;
g := Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
while J < g loop
if(I mod J = 0) THEN
if(currentSpread > ((I/J - J)/2)) THEN
currentSpread := ((I/J - J)/2);
arrayBounds := J;
end if;
end if;
J := J + 1;
end loop;
The problem I am having is with the sqrt function. I want to find the factors for the best bounds of the matrix multiplication and this was the only way that I thought to implement it.
The error I am getting is:
invalid prefix in selected component "Ada.Numerics.Generic_Complex_Elementary_Functions"
Thanks a lot for any help.
--Update
Full Code as requested:
with Ada.Text_IO;use Ada.Text_IO;
with Ada.Integer_Text_IO;
with Ada.Numerics.Generic_Complex_Elementary_Functions;
with Ada.Numerics.Generic_Elementary_Functions;
with Ada.Numerics.Complex_Elementary_Functions;
with Ada.Numerics.Generic_Complex_Types;
procedure Main is
dataFile : File_Type;
resultFile : File_Type;
value : Integer;
I : Integer := 0;
J : Integer;
currentSpread : Integer;
arrayBounds : Integer;
g : Integer;
begin
Ada.Text_IO.Open(File => dataFile, Mode => Ada.Text_IO.In_File, Name =>"C:\Users\Jeffrey\Desktop\data.txt");
while not End_Of_File(dataFile) loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Ada.Integer_Text_IO.Put(Item => value);
Ada.Text_IO.New_Line;
I := I + 1;
end loop;
Ada.Integer_Text_IO.Put(I);
I := I/2;
J := 1;
currentSpread := I;
g := Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
while J < g loop
if(I mod J = 0) THEN
if(currentSpread > ((I/J - J)/2)) THEN
currentSpread := ((I/J - J)/2);
arrayBounds := J;
end if;
end if;
J := J + 1;
end loop;
declare
type newArray is array(Integer range <>, Integer range<>) of Integer;
X : Integer := J;
Y : Integer := I/J;
Arr1 : newArray(1..Y, 1..X);
Arr2 : newArray(1..X, 1..Y);
finAnswer : newArray(1..X, 1..X);
begin
for z in 1 .. X loop
for k in 1 .. Y loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Arr1(z, k) := value;
end loop;
end loop;
for z in 1 .. Y loop
for k in 1 .. X loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Arr2(z, k) := value;
end loop;
end loop;
for l in 1 .. X loop
for m in 1 .. Y loop
for n in 1 .. X loop
finAnswer(l, n) := finAnswer(l, n) + Arr1(l, n)* Arr2(n, m);
end loop;
end loop;
end loop;
end;
Ada.Text_IO.Close(File => dataFile);
end Main;
I am using the square root exclusively to figure out the factors of a number nothing else. How I have it set up now is it will go up to the square root and then it will take the smallest spread of the factors. I do not care about rounding errors or anything else if it isn't a perfect square it can round either way.
Thanks.
Generic_Complex_Elementary_Functions is a generic package. It cannot be used directly. That is why the compiler gives you an error on this line:
Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
To use it, you have to instantiate the generic Generic_Complex_Types with the floating-point type you want to use, and then instantiate Generic_Complex_Elementary_Functions with an instance of Generic_Complex_Types. Fortunately, you don't have to go through all that if you're willing to use the built-in type Float; the language provides Ada.Numerics.Complex_Elementary_Functions for you, that uses Float as the floating-point type, or Ada.Numerics.Long_Complex_Elementary_Functions that uses Long_Float if your compiler vendors support it.
However, I don't think you want to use Complex anything. That deals with complex numbers, and I doubt that you want to use those. Use Ada.Numerics.Elementary_Functions (or Long_Elementary_Functions), which deal with real numbers.
Finally, even this isn't going to work:
Ada.Numerics.Elementary_Functions.Sqrt(I)
if I is an integer, because the argument type needs to be a Float. You'll have to use a type conversion.
Ada.Numerics.Elementary_Functions.Sqrt(Float(I))